It should be noted that I think Amy's modern design is actually pretty great as it is though! But from redesigning Rosy, I wanted to do modern Amy too!
I wanted her to look more like a hedgehog than her modern design does, but I didn't want to get rid of the general round shape and uniqueness of her quills; I didn't want to just go back to her classic design since it just shares the same quills as Sonic. I also wanted to remove her dress so she couldn't be upskirted. So I went with round but spikey quills and a shirt. (btw, she only has the three quills in the back- they go down the middle.)
Her gloves aren't bangles anymore because they look too much like Shadow's inhibitor rings. you can't see it, but her chest pattern is a heart.
A big pet peeve of mine is how female Sonic characters need to wear clothes over their entire torso but male characters don't. It's sexist because it works under the presumption that females have inherently indecent bodies. However, some Sonic female characters are recognizable purely because of their clothes, so removing said clothes is something you need to be cautious with. Amy admittedly took a long time for me to find a happy redesign for. it was very important to me that I find a good design that is recognizable and unique without deviating too much from what she's already known for, and is canonically supposed to be.
(the hammer was kind of an afterthought lol don't judge it too harshly pls)